pub fn new_birthday_probability(n: u32) -> f64 {
    if n < 2 {
        return 0.0;
    }
    let mut res = 1.0;
    for i in 0..n {
        res *= (365 - i) as f64 / 365.0;
    }
    let result = 1.0 - res;
    (result * 10000.0).round() / 10000.0 // 保留四位小数
}
